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MD Review: Pirelli Diablo Corsa III

“Racing improves the breed.” “Win on Sunday, sell on Monday.” You’ve heard and read these catch phrases many times before while learning about the latest and greatest sport bike over the years, and tires are no different. In order to keep up with the relentless pace at which the OEs develop their latest apex carvers,the major tire manufacturers have had to focus huge resources on tire development. From the user level – that’s you and me – the pressure on them to improve tires is as great, if not greater than from the OEMs. These days, sport bike owners enjoy easy access to the racetrack environment, and this is the arena in which tires suffer the greatest test of performance. It is the one in which Pirelli has over recent years developed its sport bike tire range, albeit on the world competition level. Currently, this exact tire is the spec tire for the European Superstock 600 series. What are the particulars? I thought you’d never ask….

The Corsa III designation, while applied to both the front and rear tires, pertains mainly to the rear tire and its three zones – center, left edge, and right edge, respectively. In the center portion, you’ll find the same compound as the popular Diablo Corsa, while the edges have a “new, softer” compound. The rear tire also benefits from Pirelli’s MIRS (Modular Integrated Robotized System) construction method. Construction is fully automated, with no human contact at any point of production. Jointless and uniform material distribution is claimed to produce a tire with better damping capabilities and sidewall stiffness. While speaking with Kevin Allen, Pirelli’s North American marketing coordinator, he explained with great pride that the quality and consistency of this production process is such that if you first balanced the motorcycle rim, and then mounted an MIRS produced tire, it would not need further balancing. Sounded like a challenge to me, but I had already mounted the tires and tortured them at a Streets of Willow track day (more on that later), so I’ll have to take a raincheck.

Speaking of mounting the tires, the rear tire’s soft edges were so flexible that the tire practically folded in on itself while I pushed the first side onto the rim, despite using tire mounting lube. As for balancing weight, the rear tire required no more or less than any other tire I’ve installed.

The front tire is constructed in conventional fashion, and uses a single compound that is comparable to the Pirelli Supercorsa medium compound SC2 tire. Sounds kinda boring after hearing about the rear tire, doesn’t it? Why not a dual compound front tire? Pirelli’s testing revealed that it wasn’t necessary. And maybe luck was involved, but I nearly got away with using no weight to balance the front tire.

Compounds of these tires are a compromise (as they are in all tires), and so you’ll not find grip levels equal to Pirelli’s track-only Supercorsa Pro tires, but they won’t be far off. In trade, the rider gets quicker warmup – not even a full lap before the trail braking fun kicks off, and better traction in cooler weather and wet conditions, not to mention greater wear resistance. Without being too specific about conditions and overall life expectancy, figures around 4000 – 5000 street miles were mentioned, even with the odd trackday thrown in here and there. You certainly won’t get the same sort of versatility and life from a Supercorsa Pro.

How did they perform at the track? They never misbehaved once, and took all I could intentionally – and unintentionally – throw at them. Track conditions were not that great, as it was early December. Temperatures were below freezing at 0700, and rose to a balmy 41 degrees by 0930, the time, coincidentally, that I arrived at the track. After taking a few ‘before’ photos, doing tech, a final walk around the bike (2006 GSX-R750) and tire pressure check (31 psi front, 30 psi rear), I was on the track. With it being quite chilly, being on new, cold, virgin tires seemed like a recipe for rashed bodywork if I were too impetuous, so I gave them a bit more than a full lap of cautious warmup. As promised, warmup occurred quickly, and I was soon in full knee dragging mode. Turn in was light and quick, but stable and controlled. Compared to Dunlop’s popular Qualifier, the Corsa IIIs required noticeably less effort to initiate turn-in or transition from side to side in the esses.

Time went by, the mercury rose to a high of 70 degrees and I was in track day bliss on the Pirellis. Corner drives started early, allowing me to pass a couple GSX-R1000s before the fast, right-hand Turn One. The turn called “the bowl” at the back of the course is steeply banked, and the resulting g-forces drive the tire into the ground, encouraging early and hard throttle application. Once in a while, I could feel the tire drift lazily a small amount as the banking flattened out on the exit of the bowl, but it never went beyond this the whole day.

The front tire proved to be a great accomplice in my trail braking maneuvers, as well. The very slow Turn Two is separated from turn one by only the shortest piece of straight pavement, so the front tire needs to bring its A-game if you’re going to carry a lot of speed through Turn One and Pirelli’s front hoop does exactly that, lap after lap. There was no tendency for the bike to stand up on the brakes, allowing mid-corner line changes while on the brakes with no drama. Even as my front forks bottomed out while braking hard over the bumps into downhill Turn Three, the front tire refused to budge. I was able to match the corner speeds of a few well-ridden, slick-shod bikes, one of which was a very healthy Ducati and the other a GSX-R750. Mid-corner, the only bike to better my corner speed was the sole 125 GP bike running amongst a field of big street four-strokes.

As far as wear is concerned, the front looked like it had just done a commute to work. The rear, however, showed much more wear, although it looked no worse than other tires I’ve examined post track-day. About two-thirds off the center, you could clearly see where the soft compound meets the harder center compound.

I queried Kevin Allen about the rear tire’s wear and immediately, he asked what tire pressures I used. “31 / 30.”, was my reply. He came back with “32 / 34 is what you should run.” It’s a seemingly small difference, but one that needs to be noted. The lower than optimum pressure of the rear tire allowed too much flex, which built up excess heat and caused the coarse texture as the tire tore up. Despite my neglect and abuse, the rear tire performed exactly as designed, and the front was close enough for it not to be an issue. For street riding, Allen recommended pressures of 34 front and 36 rear.

We are very impressed with these tires and their track performance. Feedback aplenty, combined with all the grip I could use, adds up to alot of confidence and a very satisfying track day experience. On the street, we continue to accumulate the miles, so keep your eyes peeled for a follow-up review exploring the Corsa IIIs capabilities as everyday companions.